This invention relates to apparatus for analyzing the constituent parts of a fluid such as blood serum. More particularly, this invention relates to blood serum analysis apparatus which ascertains the constituent parts of a blood serum sample by optical analysis at an apparatus testing station.
Apparatus of the type described conventionally utilizes a first probe for aspirating a blood serum sample and depositing such sample in a transparent laboratory vessel known as a cuvette located at the apparatus testing station. A second probe is then used to aspirate a reagent which is typically transported to the cuvette where it is contacted with the blood serum sample previously deposited therein. In accordance with techniques well known in the art, a particular reagent will bind to a predetermined constituent part of the blood serum sample, thereby isolating that part in the cuvette for subsequent optical analysis. If other parts required analysis, different reagents are ordinarily utilized.
After a particular constituent part of the blood serum sample has been isolated by contacting the sample with a particular reagent, the part may be optically analyzed by applying a beam of light to the cuvette in a well known manner. The isolated constituent part of the blood serum sample in the cuvette absorbs some of this light at different wavelengths, depending upon the characteristics of the sample. An altered light beam thus emerges from the sample under analysis, and typically passes through an optical medium which causes it to be diffracted into a plurality of discrete light components. These different light components, each characterized by a different wavelength, propagate at predetermined paths relative to the optical medium through which they pass.
Conventional optical analysis apparatus takes advantage of the fact that these discrete light components propagate at predetermined positional relationships by locating light responsive circuit elements at focusing positions along various ones of these predetermined paths. These circuit elements typically produce an electrical current signal that is proportional to the intensity of the light impinging thereon. Thus, if one such circuit element is positioned to be impinged by a light component characterized by a first wavelength, it will produce a relatively strong current signal if the relative intensity of that component is strong. On the other hand, if an adjacent circuit element is positioned to be impinged by a different light component characterized by a second wavelength, it will produce a relatively weak current signal if the relative intensity of that component is weak.
The current signals produced by such circuit elements in analog form are then electrically manipulated in a well known manner to generate a digital signal corresponding to the absorptance of the light applied to the sample isolated in the cuvette. This signal is indicative of the characteristics of that sample.
Though optical fluid analyzers of the type described have been used successfully, they are subject to certain drawbacks and deficiencies. For example, it would be highly desirable to provide improved circuitry for electrically manipulating the analog current signals produced by the light responsive circuit elements to develop the digital information corresponding to the absorptance of the light applied to the blood serum sample under analysis.
It is the object of this invention to provide such circuitry.